1. Field of the Invention
The invention relates to an oven door assembly for industrially used ovens, which oven door assembly is built up by ceramic barrier plates in a shield-type construction so as to form a distance between the ceramic barrier plates and the oven door body which distance is used as a gas channel for oven gas. The invention further relates to the ceramic barrier plates themselves.
2. Description of Prior Art
In U.S. Pat. No. 4,086,145 a coke oven door lining assembly is shown which is formed by a metallic barrier made from one I-beam which is mounted to the coke oven door body with one of the beam flanges, the other flange directing towards the coke oven interior.
The use of a metallic door assembly has in practice turned out to be disadvantageous because of the relatively high thermal expansion coefficient of the materials, mainly steel, which has been used so far. During the heating and cooling cycles in the coke oven operation the metallic very often underlies strong deformation which is due to thermal stresses and related strains and fatigue. This also very often led to blockage of the gap between the metallic barrier and the side walls of the coke oven chamber, thus disturbing the function of the gas collecting channel which acts as a pressure relief channel so as to reduce leakage through the coke oven door seal.
In the description of U.S. Pat. No. 4,217,177 a vented coke oven door apparatus is described which is constructed as a plug-type coke oven door forming a central vertical channel which is open at the top and the bottom of the plug only. The plug is formed by U-shaped ceramic bricks which are mounted with the open side directing towards the coke oven door body so that the inner surface of the U-shaped cross section forms the gas collecting channel. The bricks were supplied with recesses to receive mounting devices, especially a T-shaped bolt or for a screw with a hook-shaped end. The disadvantage of this type of construction is that the coke oven gas can enter the gas collecting channel only at the bottom of the coke oven door. Additionally, it is a major drawback of this type of construction that the U-shaped bricks, especially with the recesses for mounting devices, are very costly in the production.
From the published German patent application DE-OS No. 34 47 187 it is known to use the shield type construction for coke oven doors using replacable plates made of refractory concrete. This shield type construction consists of several ceramic front plates or barrier plates arranged vertically above each other, each of which is partly surrounded by a steel frame, each of which is mounted by three cantilever beams in a distance to the coke oven door body. Each steel frame has tie rod anchors embedded in the ceramic plate. In respect of the thermal conditions in the coke oven during coke production, especially the cyclic heating and cooling of the coke oven door, this type of mounting is disadvantageous because of the different thermal expansion of metallic and ceramic parts in the front plates.